Field of the invention

The present invention relates to a peeling station for peeling a shrimp or similar crustaceans such as small crawfish and lobsters, or a part thereof, wherein the peeling station preferably is a station for removing the tail from a shrimp and/or for removing the meat from a shrimp. The invention further relates to a system for processing shrimp comprising a clamping wheel provided with a clamp for clamping a shrimp thereon, wherein said clamping wheel is arranged to rotate along its axis of rotation to transport the shrimp clamped thereon along one or more of such peeling stations during said rotation. Additionally, the present invention relates to a method for peeling shrimp or part thereof.

Background art

Shrimp processing stations are known from Dutch patent application NL2017564, the contents of which are herein incorporated by reference and from which the present application claims priority. Earlier European patent EP 0 152 462 B1 shows a machine for processing shrimp in which one by one the shrimps are isolated exactly on time in the machine, and guided along four or six tracks per peeling machine, or a multiple thereof, so that the machine performs 60 operating strokes per minute, so that on the basis of an average of 720 shrimps per kg, an average of 4 to 5 kg of unpeeled shrimps can be processed per peeling unit per hour. Per track the machine is provided with a rotatable peeling disc adapted for clamping eight shrimp at a time, wherein during standstill of the peeling disc a tail pulling mechanism and meat removing mechanism respectively pulls a tail from a shrimp and rolls out the shrimp meat from a shrimp. The known tail removing mechanism comprises a hub, which rotates during the periodic stand still of the peeling disc, and a vertically reciprocating arm that is provided with a roll for clamping the tail of shrimp on an element of the hub. A small jet of water is provided for cleaning the roll. The known meat removing mechanism comprises a hub element which rotates during the periodic stand still of the peeling disc, as well as three satellite brushes attached to the hub, wherein during a standstill of the peeling disc one of these brushes rolls out the shrimp meat.

In order to avoid excessively damaging the shrimp meat, the known mechanisms only perform peeling of the shrimp during a periodic standstill of the peeling wheel, which adversely influences the throughput of shrimp processed by the shrimp processing machine. Even during such a periodic stand still of the peeling wheel these known mechanisms are prone to damage the meat of the shrimp and/or cause debris, such as shell parts, antennae, and/or legs of the shrimp, to become mixed with the peeled shrimp meat, e.g. when the shrimp meat is forcefully whipped out of the shell by the brushes of the meat removing mechanism, and/or in case the roll at the end of the arm of the tail removing mechanism contacts the shell of the tail of a shrimp is such a manner that the shell is partially crushed.

US 4,385,422 describes an apparatus for deheading and peeling crayfish comprising pairs of gripper assemblies for operative engagement with the head and tail sections of a crayfish, respectively, supported for movement in synchronized relation through separate but tangentially related orbits wherein the pairs of grippers simultaneously move in a common direction through or past the point of tangency of their respective orbits wherein the tail holding gripper assemblies each comprise a lower crayfish pan constructed from flexible rubber or plastic member having an arcuate cross section greater than 180° and a top arm member pivotably mounted above the lower pan to hold the crayfish in the pan during the deheading cycle, the pivoting of top arm member being actuated by a simplified cam assembly.

It is an object of the present invention to provide a peeling station and method for more gently peeling a shrimp or portion thereof.

If is a further object of the present invention to provide such a peeling station and method which allow a high throughput of shrimp through a shrimp processing system.

Summary of the invention

To this end, according to a first aspect, the present invention provides a station for peeling a shrimp or part thereof while said shrimp is individually clamped on a clamping wheel that is rotatable along said station around an axis of rotation, said station comprising: a base; a rotor connected to said base to be rotatable relative to said base around a first axis of rotation in a predetermined direction of rotation for at least a complete revolution; and one or more grippers, each attached to said rotor around an associated second axis of rotation parallel to said first axis of rotation and spaced apart therefrom, wherein each gripper is rotatable relative to said rotor around its associated second axis of rotation and is arranged for gripping a portion of said shrimp when said gripper is moved to a position close to where said shrimp is clamped on said clamping wheel during rotating movement of said rotor around the first axis of rotation while said gripper rotates relative to said rotor around its associated second axis of rotation, to separate said portion of said shrimp from a part of said shrimp which remains clamped on the clamping wheel.

The position of the base is generally stationary relative to the axis of rotation of said clamping wheel, whereas position of the one or more the grippers relative to said axis of rotation of the clamping wheel changes during rotation of the rotor relative to the base. The rotation of the gripper relative to the rotor during rotating movement of the rotor allows smooth engagement of the gripper with the portion of the shrimp to be gripped, and once said portion is gripped there is no, or relatively little movement between said portion and the gripper. This results in gentle treatment of the gripped portion of the shrimp. At the same time the part of the shrimp which remains clamped on the clamping wheel is not contacted by the gripper and thus remains substantially unaffected thereby. The arm of rotation of the gripper, i.e. a distance between the axis of rotation of gripper on the rotor and that part or those parts of the gripper engaging the portion of the shrimp, can be small as the gripper is rotatably supported on the rotor. This in turn allows the gripper to be rotated relatively slowly around its associated axis of rotation on the rotor when gripping said portion, resulting in low impact between the gripper and the portion of the shrimp when said portion is being engaged by the gripper. Preferably, at any time the gripper is in contact with the portion of the shrimp, the length of said arm is less than the radius of the rotor. Also preferably, at any time the gripper is in contact with the portion of shrimp, the angular velocity of the gripper relative to the rotor remains below 3 or 4 times the angular velocity of the rotor relative to the base.

The gentle treatment of the portion of the shrimp that is gripped allows a station of the present invention to be used at higher peeling rates, i.e. number of shrimp peeled per unit time, than prior art peeling stations, while causing no or substantially less damage to the shrimp meat. Gripping of a portion of the shrimp by the peeling stations of the invention can be performed in such a gentle manner that the gripper can engage the portion of the shrimp during continuous rotation of the clamping wheel without significantly damaging the shrimp meat or mixing the meat with debris. Throughput of shrimp through a shrimp processing system provided with one or more peeling stations according to the invention can thus further be increased.

In a preferred embodiment, those parts of each of said grippers that come into contact with a shrimp, e.g. the gripping surface(s) of each gripper, are adapted for gripping the portion of the shrimp without piercing or puncturing the shrimp meat. The gripping surfaces are thus free from spikes or tines which can pierce through the shell of a shrimp and into the meat.

In an embodiment each of said one or more grippers is adapted for, once it has gripped the portion of the shrimp, holding said portion substantially stationary relative to said gripper during rotation of the rotor around the first axis of rotation, at least until said gripper has moved away from said position where said remaining part of the shrimp clamped on said clamping wheel is located. In this manner damage to the portion or the shrimp by the gripper is substantially prevented. The gripper thus holds the portion of the shrimp to separate it from the part of the shrimp which remains clamped on the clamping wheel, rather than whipping the portion of the shrimp away from the remaining part. Once the gripper has moved to a position spaced further apart from the clamping wheel, the gripper can be moved relative to the portion of the shrimp to release said portion from the gripper. Preferably, for gripping the portion of the shrimp, the gripper is adapted for moving, during said rotation thereof around its associated second axis of rotation, between a first position in which it is spaced apart from said shrimp clamped on said clamping wheel, to a second position in which it engages said portion of said shrimp in order to hold said portion stationary to said gripper, in particular during continuous rotation of said clamping wheel.

In an embodiment the rotor is adapted for rotating simultaneously with the clamping wheel, i.e. at the same time. To this end rotation of the rotor and clamping wheel may be mechanically linked, e.g. via chains and sprockets, though preferably they are both provided with a respective driving means, such as an electromotor, connected to a controller for driving said simultaneous rotation. The speed of rotation of the rotor and the clamping wheel does not have to be the same, as long as any time a shrimp clamped on the clamping wheel passes the station, the rotor is moved such that a gripper is moved to the portion close to where said shrimp is clamped on the clamping wheel in order to grip the portion of said shrimp. In an embodiment said base is provided with an meshing section arranged for meshing with a portion of one of said one or more grippers during rotation of said rotor around the first axis of rotation such that the gripper is caused to rotate relative to said rotor around its associated second axis of rotation. Thus, rotation of the gripper is caused by rotation of the rotor, and only drive means for driving rotation of the rotor relative to the base need to be provided. Such drive means preferably comprises an electric motor. The meshing section which meshes with the portion of one of said grippers preferably comprises at least circular segment covering an arc of between 5 and 120, but may alternatively cover a complete circular arc of 360 degrees. Preferably, the position of the meshing section is stationary relative to the base during peeling of a shrimp or portion thereof, though the position of the meshing section relative to the periphery of the clamping wheel may be adjustably when the station is not in operation, e.g. by rotating the meshing section around the first axis of rotation, in order to adjust the position where the gripper grips a shrimp that is clamped on the clamping wheel. The portion of each gripper that is adapted for meshing with the meshing section may be provided on a shaft of the gripper, said shaft having a longitudinal axis which coincides with the associated axis of rotation of the gripper, and wherein rotation of the shaft relative to the rotor causes a corresponding rotation of the gripper.

In an embodiment said meshing section comprises a toothed section and wherein said portion of said one of said one or more grippers comprises a toothed gear for engaging said toothed section. This prevents the portion of the gripper from slipping when in contact with the meshing section, so that corrected rotation of the gripper relative to the rotor when the portion contacts said meshing section is guaranteed.

In an embodiment the base comprises a contact surface arranged between the first axis of rotation and the axis of rotation of the clamping wheel, and wherein each of the grippers is provided with a catch surface spaced apart from its associated second axis of rotation and rotatable around an axis parallel to the second axis of rotation, wherein the catch surface is adapted for catching the contact surface to drive rotation of the gripper relative to the rotor around its second axis of rotation.

Preferably the catch surface has a concave shape arranged for sliding along the contact surface during contact therewith. More preferably, the contact surface is formed by a pin extending in a direction parallel to the first axis of rotation.

In an embodiment said one or more grippers are constituted at least by a first gripper and a second gripper, wherein said grippers are spaced along the circumference of the rotor. Thus, the first gripper, while not engaging any shrimp portion, may approach the position close to where a shrimp is clamped on the clamping wheel in order to grip said portion while at the same time the second gripper is moved away from the clamping wheel while still clamping a portion of a shrimp which was separated from a directly preceding shrimp on the clamping wheel. Preferably the one or more grippers further comprise a third gripper. In this case, during said movement of the first and second grippers, the third gripper is moved to another position spaced further apart from the clamping wheel, where the portion of the shrimp held by the third gripper can be released and after which the third gripper can be cleaned, for instance using brushes and/or water jets. Once the third gripper has been cleaned, e.g. using a jet of water and/or air, and or using a brush, and preferably dried if water was used during cleaning thereof, the third gripper can be used to pick up the next shrimp from the clamping wheel.

In an embodiment said station further comprises a cleaning section arranged for cleaning each gripper of said one or more grippers when a distance between said second axis of rotation to the periphery of said clamping wheel is greater than a distance between said first axis of rotation and said periphery of said clamping wheel and while said gripper is not in contact with meat of the shrimp. The cleaning section preferably comprises a brush and/or a supply of liquid for arranged cleaning all portions of the gripper that were in contact with the portion of the shrimp. By arranging the cleaning section spaced apart from the periphery of the clamping wheel, it is substantially prevented that water used during cleaning and/or debris swept of the gripper during cleaning is transported onto the clamping wheel or onto shrimp or shrimp meat clamped thereon. As the entire gripper rotates along with the rotor, cleaning of all portions of the gripper that were in contact with the portion of the shrimp can be performed by only single cleaning section, i.e. it is not necessary to have one cleaning section arranged relatively close to the periphery of the clamping wheel for cleaning one portion of the gripper which is moved along with the rotor, and a separate cleaning section spaced further apart from said periphery for cleaning another portion of the gripper which remains closer to the clamping wheel. The cleaning section is adapted for substantially removing any pieces of the portion of the shrimp adhering to the gripper. Though preferably the gripper will have released the portion of the shrimp before reaching the cleaning section, alternatively the cleaning section may be used to facilitate removal of said portion from the gripper.

In an embodiment said station is a tail pulling station, wherein said rotor is adapted for rotating in a same predetermined direction of rotation as said clamping wheel, and wherein each of said one or more grippers is adapted to rotate relative to said rotor in a direction of rotation opposite to said predetermined direction of rotation to grip a tail portion of said shrimp between the gripper and an associated clamping surface of the rotor, which clamping surface coincides with a portion of the circumference of the rotor, preferably while said rotor and said clamping wheel rotate in the same direction of rotation. The tail pulling station can remove the tail portion during continuous rotating motion of the clamping wheel without puncturing the shrimp with tines or the like, so that the meat of the shrimp remains substantially undamaged. Each gripper has its own associated clamping surface on the rotor. During a complete revolution of the rotor, each of the one or more grippers remains attached to the rotor, so that any distance between the gripper and its clamping surface between which the tail portion is to be gripped can be closed by a relatively small and slow movement of the gripper, resulting in a low impact between the gripper, the surface and the tail portion of the shrimp. The clamping surface will typically extend substantially parallel to the second axis of rotation.

The gripper may comprises an elastic spring section for allowing the gripper to bend when gripping the tail portion of the shrimp, preferably wherein a distal end of said gripper comprises a roller for making rolling contact with the tail portion of the shrimp. The bending of the gripper and/or the rolling contact of the gripper with the tail portion ensure that the tail of each shrimp is gripped smoothly, even for differently sized shrimp, and without crushing the tail portion or damaging the meat of the shrimp.

In an embodiment, the effective arm between the gripper's roller 13 and its second axis of rotation A2 is adjustable, for adjusting a force that can be applied by the roller on a portion of a shrimp. The force exerted by gripper on the tail portion can thus be adjusted depending on the kind of shrimp in the batch of shrimp. It will be appreciated that this adjustment is not carried out during rotation of the rotor, but for instance when a new batch of shrimp of a different kind than was being processed before is to be processed.

In an embodiment the clamping surface comprises an abrasive surface finish. This improves gripping of the shrimps between said surface and the gripper. The abrasive finish preferably comprises non-toxic abrasive grains, such as diamond grains and/or cubic boron nitride grains held to the surface by means of a non-toxic adhesive such as a tin or silver solder. Most preferably the abrasive finish is formed as a layer of non-toxic solder in the non-toxic abrasive grains are embedded, e.g. by first applying a first layer of the solder on the clamping surface, next depositing the grains on said first layer, and subsequently applying a second layer of said solder, preferably of about a same thickness as the first layer, on said first layer in order to embed the grains. The resulting finish is particularly wear resistant as the second layer of solder helps prevent the grains from detaching from the clamping surface. Contamination of the peeled shrimp meat by the abrasive surface finish is thus prevented. In addition, the resulting finish is resistant to oils and/or fats materials such as may be present on the shrimp and allows easy cleaning. The surface finish preferably has a maximum thickness between 0,1 mm and 0,4 mm, more preferably about 0,2 mm. The diamond or cubic boron nitride grains in the surface finish preferably have a grit of between D/B 151 and D/B 215 according to FEPA (Federation of European Producers of Abrasives) standard 42-1 :2006, and/ or a grit corresponding to a grit of between P60 and P100, more preferably around P80.

Preferably each clamping surface that is provided with the abrasive surface finish is provided on a detachable plate that is detachably attached to the rotor. Such a detachable plate is easily replaced with another detachable plate, e.g. having a clamping surface with an abrasive surface finish of a different grit.

In an embodiment, each clamping surface of said rotor associated with a gripper of said rotor lies on the outer circumference of the rotor, wherein all said clamping surfaces are circumscribed by a virtual cylinder, wherein each gripper is rotatable around its associated second axis of rotation from a position wherein a portion of said gripper is arranged outside of said virtual cylinder, to a position wherein said gripper is arranged completely within said virtual cylinder. The gripper can thus be folded away when not gripping and/or when not being cleaned.

In an embodiment said station further comprises one or more biasing elements for biasing said one or more grippers to a position away from its associated clamping surface of said rotor. The biasing element ensures that when each gripper approaches the position close to where the shrimp is clamped on said clamping wheel, the gripper is sufficiently far removed from its corresponding clamping surface to allow the tail portion of a shrimp to be gripped therebetween. Preferably each of the grippers is connected to a first end of a respective biasing element, wherein another end of the biasing element is attached stationary relative to the rotor. For instance, each gripper may be attached to the rotor by means of a shaft which is rotatable around the second axis of rotation, wherein a biasing element in the form of a torsion spring is at one end connected to said shaft and at another end attached stationary relative to rotor. As another example, each gripper may be rotatable around a shaft that is fixed to the rotor, with a biasing element connected at one end to the rotator and at another to the gripper.

In an embodiment said station is a meat removing station wherein said rotor is adapted for rotating in a direction of rotation counter to the direction of rotation of said clamping wheel, wherein each of said one or more grippers is adapted for gripping said the meat of a shrimp along lateral sides of the meat during said rotating movement of said rotor around the first axis of rotation while said gripper rotates relative to said rotor around its associated second axis of rotation to separate the meat of the shrimp form the shell of the shrimp which remains clamped on the clamping wheel. Preferably, each of said one or more grippers is adapted for rotating for one or more complete revolutions around its associated second axis of rotation in a same direction of rotation as the rotor.

In an embodiment, each gripper comprises two facing surfaces for contacting the sides of the meat therebetween, wherein the gripper is adapted for smoothly moving the facing surfaces towards and subsequently away from each other during a complete rotation of said gripper. The facing surfaces, at least when not gripping a portion of a shrimp, will generally extend substantially normal to the associated second axis of rotation of said gripper.

In an embodiment, said facing surfaces are provided with a ceramic coating, e.g. having a thickness of in the range of 10 to 100 micron, preferably about 60 micron. The ceramic coating reduces the friction on the shrimp meat during gripping and is easily cleaned while being resistant to wear and scratching, in particular when compared to polytetrafluoroethylene coatings. The coating preferably has a kinetic friction coefficient of 0.2 or less and may be applied to each of the facing surfaces by means of a thermal spraying process, in particular by means of a flame spray or arc spray process, after which the applied coating may be polished.

In an embodiment each gripper is provided with a biasing member for urging the two facing surfaces to a predetermined position and/or orientation relative to each other. For moving the facing surface away from each other, the gripper is preferably provided with a biasing member, e.g . a coil spring, for spacing said first and said second gripping surface apart from each other parallel to said second axis of rotation. When the gripper approaches the position close to where said shrimp is clamped on said clamping wheel, the two surfaces can thus be spaced sufficiently far apart from each other to allow the shrimp to be engaged by said surfaces on its corresponding lateral sides. Additionally or alternatively, each gripper may be provided with one or more further biasing members for urging the two facing surfaces towards each other along a direction parallel to said second axis of rotation. For instance, one further biasing member may be provided for urging one of said two facing surfaces in a direction parallel to the second axis of rotation, whereas another further biasing member may be provided for urging the other of the two facing surfaces in an opposite direction parallel to the second axis of rotation. When making contact with the shrimp meat, either of both of the surfaces which engage the meat can thus be resiliently moved relative to said portion, while the meat is being gripped between the surfaces. The same gripper can thus be used for gripping meat of different shrimp which have different sizes, in particular having different widths, without substantially damaging the shrimp meat.

In an embodiment, one or both of said two facing surfaces is translatable along said second axis of rotation, in particular while said two surfaces are oriented substantially parallel to each other. The second axis of rotation will typically coincide with a center axis of a shaft on which the gripper is supported, with one or both of the gripping surfaces slidably supported on said shaft.

In an embodiment one or both of said facing surfaces is adapted for rotating around an axis perpendicular to said second axis of rotation, wherein said perpendicular axis preferably intersects said second axis of rotation. When a portion of the shrimp is gripped, the facing gripping surfaces may thus move somewhat relative to each other such that the angle there between can be varied. This allows better contact with the portion of the shrimp to be gripped. For instance, the facing surfaces may be moved from an orientation in which they are substantially parallel to a different, non-parallel, orientation. Biasing members may be provided for urging the two facing gripping surfaces to be substantially parallel to each other, said biasing members preferably comprising or consisting of the biasing members and/or further biasing members described earlier herein.

In an embodiment each of said grippers comprises a shaft supporting said facing surfaces and coinciding with the associated second axis of rotation of the gripper, wherein one or both of said facing surfaces are supported by said shaft to be translatable relative to said shaft along the second axis of rotation and rotatable around an axis perpendicular to said second axis of rotation. The facing surfaces may for instance be supported on the shaft via springs, or via a ball-joint.

In an embodiment said meat removing station comprises, or is coupled with, a head stopper station provided with a reciprocating arm, preferably with a roller at a distal end thereof, wherein said head stopper station is arranged, in the direction of rotation of the clamping wheel, next to and after the position where the grippers of the meat removing station can engage a shrimp that is clamped on the clamping wheel, and wherein said head stopper station is adapted for moving said arm towards the clamping wheel such that the arm, or roller at the end thereof, applies a pressure on the leading portion of a shrimp held by the clamp while the meat is being removed from the shrimp by the grippers of the meat removing station, and for retracting the arm away from the clamping wheel when the meat has been substantially removed so that the remaining portion of the shrimp on the clamping wheel can pass beyond the head stopper station. The head stopper station allows the meat removing station to more effectively remove of meat from the shrimp. Preferably, the clamping wheel also adapted for, when a shrimp clamped thereon reaches a position where it can come into contact with the arm or roller at the end of the arm, at least partially loosening the clamp which clamps said shrimp, so that the meat can be more easily removed from its shell. In such a case the head stopper station further aids in removing the meat as it also ensures that the part of the shrimp that is not gripped by the gripper remains held against the clamping wheel. When the meat has been removed from the shrimp, and before or during retraction of the arm, the clamp is preferably brought back to its clamping position for clamping the remaining shell on the clamping wheel until it can be disposed of.

In an embodiment all parts of said station that come into contact with the shrimp meat are completely brushless, preferably wherein no part of the shrimp meat is contacted by a brush during processing by said station. Thus, in the tail removing station the clamping surfaces and the rollers are brushless, as is preferably the entire rotor, so that during processing by the tail removing station the shrimp meat which is still attached to the portion of the shrimp clamped on the clamping wheel, does not come into contact with any brush. In the meat removing station the gripping surfaces are completely brushless, as is preferably the entire rotor, so that the shrimp meat does not come into contact with a brush, regardless of whether the meat has already been separated from the portion of the shrimp that remains clamped on the clamping wheel or not.

In an embodiment all parts of said station that comes into contact with the shrimp meat are substantially free from water during contact with the shrimp meat, preferably wherein no part of the shrimp meat is contacted by water during processing by said station. This may be achieved by means of a cleaning section as described earlier herein, wherein each gripper is preferably dried, e.g. using a blast of air, after being cleaned and before gripping a portion of another shrimp that is clamped on the clamping wheel.

According to a second aspect, the present invention provides a system for peeling shrimp, comprising: one or more stations as described herein; a transport unit adapted for individually transporting shrimp between said stations, said transport unit comprising a frame and said clamping wheel mounted rotatable relative to said frame around an axis of rotation, said clamping wheel being provided with a plurality of clamps each adapted for clamping an individual shrimp, wherein said clamping wheel is adapted for continuously rotating in a predetermined direction of rotation for one or more complete revolutions; and wherein said one or more stations are arranged along the circumference of the clamping wheel and adapted for peeling a shrimp or part thereof while said shrimp is individually clamped on the clamping wheel during said continuous rotating movement of said clamping wheel. Each station is arranged along the circumference of the clamping wheel and with its base stationary relative to the axis of rotation of the clamping wheel in such a manner that during rotation of the clamping wheel the grippers of the stations can approach the clamping wheel to grip a portion of a shrimp.

In an embodiment said one or more stations comprise a first series of stations arranged along the circumference of said clamping wheel, wherein the transport unit comprises multiple further clamping wheels arranged in parallel with said clamping wheel and connected, together with said clamping wheel, rotationally fixed to a common shaft for driving rotation of said clamping wheels, wherein along each of said further clamping wheels a further series of stations as described herein is arranged, with each station in each of said further series corresponding to a station of said first series and arranged with its first axis of rotation substantially coinciding with the first axis of rotation the corresponding station of the first series, wherein the rotor of each station of the first series and the rotors of the corresponding stations in the further series are rotationally fixed to a common shaft for driving rotation of said rotors. Herein, corresponding stations are of a similar construction and/or have a similar peeling function. For instance, the transport unit may comprise a clamping wheel and a number of parallel further clamping wheels, all connected to a common shaft, wherein along each clamping wheel is provided a series of stations which may include one or more of a cutting station for making an incision in a ventral shell part of the shrimp, a tail pulling station as described herein, a ring removing station for removing an abdominal ring of the shell, and a meat removing station as described herein. Such a system with 1 clamping wheel and 5 further clamping wheels could comprise 6 tail pulling stations connected to a common shaft and 6 meat removing station connected to another common shaft.

In an embodiment a separate electromotor is attached to each of said common shafts, said system further comprising a controller for controlling the electro motor that is connected to the common shaft for driving rotation of the clamping wheels to rotate substantially continuously at a first speed, and for controlling the electro motors that are connected to the remaining common shafts in dependence of said first speed. The controller can thus ensure correct timing for the stations in dependence of the rotational position of the clamping wheels. The electro motors preferably are servo motors and/or provided with encoders to allow accurate determination of the rotational position of each common shaft.

In an embodiment the rotors between corresponding stations are rotationally offset with respect to each other, for peeling differently size shrimp on different clamping wheels of said clamping wheel and further clamping wheels. On each clamping wheel a batch of shrimp can thus be processed, wherein between batches the shrimp may have different sizes, e.g. different lengths and/or widths.

According to a third aspect, the present invention provides a method for peeling a shrimp or part thereof while said shrimp is individually clamped on a clamping wheel that is rotatable along a peeling station around an axis of rotation, said method comprising, during continuous rotating movement of the clamping wheel: moving a gripper of said peeling station, from a starting position, along a circumferential path defined by said peeling station to a position close to where said shrimp is clamped on said clamping wheel; subsequently causing said gripper to grip a portion of said shrimp by driving rotating movement of said gripper around an associated axis of rotation thereof while said axis of rotation moves in conjunction with said gripper along said circumferential path; and moving said gripper further along said path to separate said portion of said shrimp from a part of said shrimp which remains clamped on the clamping wheel, and moving said gripper along the circumferential path back to the starting position. The circumferential path along which the axis of rotation of the gripper is moved may for instance be defined by a rotor of the peeling station. This method is particularly well suited to be used with a station or system of the present invention. Short description of drawings

The present invention will be discussed in more detail below, with reference to the attached drawings, in which:

Fig. 1 shows a system for peeling shrimp according to the present invention,

Figs. 2A schematically shows a side view a first embodiment of a station according to the present invention, in the form of a tail pulling station,

Figs. 2B and 2C show perspective views of the tail pulling station, respectively with the gripper in an open position and a closed position;

Figs. 3A - 3C illustrate operation of the station according to the first embodiment;

Figs. 4A and 4B illustrate a tail pulling station having an alternative mechanism for driving rotation of the gripper relative to the rotor;

Fig. 5A and 5B respectively show schematically an isometric view and a side view of a second embodiment of a station according to the present invention in the form of a meat removing station,

Figs. 5C shows a cross-sectional view of gripper 122 through its second axis of rotation A3 Figs. 6A-6C illustrate operation of the station according to the second embodiment, Fig. 7 shows an isometric view of a head stopper as may be part of a meat removing station according to the invention.

Description of embodiments

Fig. 1 schematically shows a side view of a system 1 for peeling shrimp. Shrimp are individually supplied to the system 1 from a slide chute 5. When leaving the downstream end 5.1 of the chute 5, each shrimp comes into contact with a push wheel 8 which rotates around its central axis in direction of rotation R4 to push the shrimp towards a transport unit 10 which. The transport unit 10 comprises a clamping wheel 10.1 which is provided with several clamps, each for clamping a single shrimp, and rotates in a direction of rotation R5. The push wheel 8 is arranged between the downstream end of the slide chute 5 and a stop mechanism 9. The stop mechanism 9, at least when in contact with a shrimp, rotates in a direction of rotation R6 that is counter to a direction of rotation R5 in which the transport unit 10 rotates around its centre axis. The stop mechanism 9 stops the shrimp when it has left the downstream end 5.1 of the chute 5 and prevents the shrimp from sliding out of the clamp of the transport unit 10 before the clamp has properly clamped the shrimp. Each shrimp can thus be clamped on the clamping wheel 10.1 during continuous rotation of the clamping wheel.

Once the shrimp has been clamped on the transport unit 10, the shrimp is transported head first and dorsal side up by continuous rotation of the clamping wheel 10.1 in direction R5, along peeling stations 12, 13, 15, 16 and 17 which are arranged along about half of the circumference of the clamping wheel 10.1. A frame 50, here shown schematically, is provided for stationarily supporting a base of each of the peeling stations. In order of position along the circumference of the clamping wheel 10.1 in the direction of rotation R5 of the clamping wheel 10.1 , the peeling stations comprise a cutting station 12 that is provided with tail stretcher 11 and with a rotary knife 12.1 for making an incision in a ventral shell part of the shrimp, a tail pulling station 13, a ring removing station 15, for removing an abdominal ring of the shell, and a meat removing station 16 for removing the shrimp meat, or peeled meat, from the remaining portion of the shrimp that is clamped on the transport unit 10. During processing of a shrimp by the meat removing station 16, and while the clamping wheel 10.1 continues its rotation, a rotatable roller 17.1 of a head stopper station 17 is moved in the direction of the clamping wheel to provide pressure on the head of the shrimp while the meat is removed. Though the head stopper station 17 is shown separate from the meat removing station, it is coupled to the meat removing station 16, or alternatively may even be part of the meat removing station. The head stopper station 17 is preferably also coupled to the clamping wheel 10.1 , mechanically or by control means for controlling movement of the clamping wheel and the head stopper station 16, to cause the clamp of the clamping wheel which holds the shrimp to be slightly loosened when the head stopper station 17 pushes the head of shrimp against the clamping wheel 10.1. In this manner the meat of the shrimp can be more easily removed from the shell by the meat removing station 16. Once the meat is removed, the roller 17.1 of the head stopping station is moved away from the clamping wheel 10.1 so that the remaining portion of the shrimp that is still clamped by the clamp can pass the head stopping station without being blocked and without pressure being exerted thereon by the roller.

The shrimp meat that is removed falls down direction P5 and is collected in container 20.

That portion of the shrimp that is still held by a clamp of the transport unit 10 is released before the clamp reaches the position where another shrimp is supplied from the chute 5 into the same clamp, and the process is repeated. Throughout processing of the shrimp in the system 1 all parts of said processing stations 12, 13, 15, 16 and 17 that are adapted to come into contact with the shrimp meat are completely brushless to avoid damaging the meat. During brushing of these parts of the processing stations and the clamps of the clamping wheel, the brushes 14a, 14b, 14c only contact those parts which at that time are not in contact the meat of the shrimp and/or a portion of the shrimp that is further to be processed. Likewise, all parts of said processing stations that do come into contact with the shrimp meat are substantially free from water during said contact, though those parts may be cleaned using water when they are not in contact with shrimp meat and/or a portion of the shrimp that is further to be processed. Further details of this system are described with reference to Fig. 5 of Dutch Patent application NL 2017564 to applicant, from which priority is claimed. Figure 2A shows a detail of a first embodiment of a peeling station according to the present invention, in the form of the tail pulling station 13 of Fig. 1. The station comprises a rotor 13.1 which is rotatably connected to a stationary base 13.2 having a ring 13.2 that is arranged stationary to the frame 50. For reasons of clarity only the ring of the base 13.2 is shown, though it will be understood that the ring itself may be supported for instance directly on the stationary frame, or via other parts of the base (not shown) that are stationary to the frame 50, or may even constitute the base. The ring 13.2 comprises a toothed section 13.6 at its inner circumference near the clamping wheel 10.1. The toothed section is arranged for meshing with respective toothed portions of gears 13.43, 13.44, 13.45 of grippers 13.13, 13.14, 13.15.

Each of the grippers is rotatably connected to the rotor 13.1 around an associated second axis of rotation A2 which extends parallel to the first axis of rotation A1 of the rotor 13.1 and is spaced apart therefrom. The toothed section 13.6 only extends along the circumference of the ring 13.2 over an angle during which one of the grippers 13.13, 13.14, 13.15 should grip, or should be moved to grip, the tail of a shrimp. In the embodiment shown this angle a extends over about one twentieth of the circumference of the ring, i.e. is about 18 degrees, though angles in the range of 10 to 30 degrees have also been found to work. When the toothed section 13.6 is engaged by one of the gears 13.43, 13.44 and 13.45 which are attached to the respective grippers 13.13, 13.14 and 13.1 and which are rotatable relative to the rotor 13.1 , the gear causes the corresponding gripper to rotate in a direction R2 relative to the rotor 13.1 , which is opposite to the rotational direction R1 of the rotor 13.1. This results in the tail of the shrimp being gripped between the respective roller 13.23, 13.24, 13.25 that is provided at the end of each gripper 13.13, 13.14 and 13.15 and a corresponding rotor surfaces 13.3, 13.4, 13.5 while the portion of the shrimp that is clamped on the wheel continues to be moved in direction R5, and the tail T is pulled away therefrom in direction R1 , so that the tail portion of said shrimp is separated from the part of said shrimp which remains clamped on the clamping wheel 10.1.

In the side view shown, between the rotor surfaces 13.3, 13.4, 13.5 the rotor comprises spaces, or recessed portions, 13.33, 13.34, 13.35, adapted for at least partially accommodating therein a roller of a gripper when said gripper is not in the position close to where the shrimp is clamped on the clamping wheel. Thus, each gripper can rotate around its associated axis of rotation A2 from a position in which it is substantially or even completely arranged within a virtual cylinder which circumscribes the rotor surfaces 13.3, 13.4, 13.5, to a position in which it at least its gripping end, e.g. its roller, is arranged outside of said cylinder.

Only gripper 13.13, of which the gear 13.43 engages the toothed section 13.6, is shown in Fig. 2A with its roller close to its corresponding rotor surface 13.3. The other two grippers 13.14, 13.15 whose gears are not in contact with the toothed section 13.6 are biased, e.g. by spring members, to move back to a position in their corresponding space 13.34, 13.35 closer to the axis of rotation A1. Such a spring member 13.63 for gripper 13.13 is schematically shown in Fig. 2B to be connected to a corresponding rotatable shaft 13.73 of said gripper 13.13. The spring member 13.63 is a torsion spring with one end which stationary to the frame 50, and with its other end connected to the shaft 13.73 which is rotation fixedly connected to the gripper 13.13. When the gear 13.43 does not engage the toothed section 13.6, the spring 13.63 will cause gripper 13.13 to rotate back to a non-gripping position in which the gripper is substantially accommodated in space 13.33 of the rotor. The perspective view of Fig. 2B shows the tail pulling station 13 arranged next to a clamping wheel 10.1 on which three individually clamped shrimp S are schematically shown. For reasons of clarity the actual clamps of the clamping wheel 10.1 are not shown in Fig. 2B, but similar clamps are illustrated in Fig. 4B of the priority application. After a shrimp S clamped on the clamping wheel has passed the cutting station 12, it is transported by the clamping wheel towards the tail pulling station 13. Here the tail portion T, which had previously been stretched at cutting station 12, can bend back, so that the tail portion T at least partially projects into the space 13.33. At the position where it transitions into the space the surface 13.3 is provided with a centering recess, which extends substantially along the circumferential direction, and which helps to align the tail T of the shrimp S with respect to said surface 13.3 so that the tail extends substantially within the plane of the clamping wheel instead of at an angle to said plane.

Fig. 2C shows the same tail pulling station in which the rotor has rotated a bit further along direction of rotation R1 , so that the gripper 13.13 of which gear 13.43 engages toothed section 13.6 has rotated further along direction R2. The roller 13.23 has moved out of the space 13.33 to clamp the tail portion T between the roller and the corresponding clamping surface 13.3 of the rotor 13.1. The tail portion has thus been separated from the portion S of the shrimp that is still clamped on the claiming wheel 10.1.

If required, the effective arm length between the gripper's roller 13 and its second axis of rotation A2 may be adjusted. For instance for gripper 13.13 this effective arm length may be adjusted by first loosening screws, 13.61 which extend through a slit 13.60 in the gripper which extends along direction L. Subsequently the arm 13.13 may be slid along direction L relative to arm portion 13.72 which is fixed to the gear 13.43, and the screws 13.61 be tightened again at a different positions along the slit 13.60. By adjusting the effective arm length, the force that the roller 13.23 can apply to a portion of a shrimp is adjusted as well.

Figs. 3A-3C schematically illustrate how initial cuts are made in the shell of the shrimp and how subsequently the tail is pulled off using the tail pulling station 13 shown in the previous figures. Fig. 3A starts when a curled shrimp S has been clamped on a clamp of the clamping wheel 10.1 just after the shrimp has been supplied to the wheel, e.g. from the downstream edge of chute 5 of figure 1. Curling of the shrimp may have occurred during boiling of the shrimp e.g. prior to being placed in the receptacle. During transport of the shrimp S along the direction of rotation R5, and at least partially while a cut is made in the ventral side of the shrimp by rotating knife 12.1 , the tail T of the shrimp is held back by tail stretcher 1 1 . The tail stretcher 1 1 contacts the tail at location that is spaced apart further from the center of the clamping wheel 10.1 than the contacting edge of rotating knife 12.1 , so that in principle that portion of the shrimp that is clamped, i.e. the lateral sides of the shrimp, can be moved under the tail stretcher 1 1 without making contact with the tail stretcher 1 1.

With the shell section of the shrimp which connects the tail shell part to the rest of the shrimp weakened by the incisions, the shrimp S is subsequently transported to tail pulling station 13 which is provided with a rotor 13.1 which rotates in a direction R1 that is the same as direction or rotation R5 of the clamping wheel. The rotor 13.1 has three clamping surfaces 13.3, 13.4 and 13.5 that are rotationally fixed with respect to the rotor, and further comprises three respective elastic grippers, only one of which, gripper 13.13, is shown in Figs. 3A-3C.

Fig. 3A shows that the tail T of a shrimp S, once the shrimp has passed the cutting station 12, can spring at least partially back to an unstretched, or bend, state before reaching tail pulling station 13. Fig 3B shows that clamping surface 13.3 of the rotor 13.1 at least partially stretches the tail T of the shrimp again when the rotor 13.1 and the clamping wheel 10.1 both rotate continuously in same directions of rotation R5 and R1. During said stretching, the gripper 13.13 rotates relative to the rotor in a direction R2 counter to R1 , so that the tail of the shrimp is gripped between the roller 13.23 at the end of the gripper 13.13 and the clamping rotor surface 13.3, as shown in Fig. 3B. Continued rotation of both the rotor 13 and the clamping wheel 10.1 causes the tail to be pulled off the shrimp, as shown in Fig. 3C. When the rotor then continues its rotation, the gripper 13.13 releases the tail portion of the shrimp so that it can be disposed of before the rotor surface is cleaned by brush 14A.

Figs. 4A and 4B schematically show a tail pulling station 13' according to the invention, with a rotor 13'.1 on which a different mechanism for driving rotation of the gripper 13.13 relative to the rotor is provided than shown in Figs. 3A-3C. The station 13' comprises a contact surface 13.32, here in the form of a pin which extends parallel to the axis of rotation of the rotor. The contact surface 13.32 is arranged stationary with respect to the base of the rotor, and is positioned between the first axis of rotation A1 of the rotor 13'.1 and the axis of rotation of the clamping wheel 10.1. When the rotor rotates in direction of rotation R1 , from the position shown in Fig. 4A to the position shown in Fig. 4B, the contact surface is caught by a convex side of a convex catch surface 13.33 which is fixed to the gripper 13.13 and is spaced apart from the gripper's second axis of rotation A2. The gripper 13.13 is driven to rotate in a direction opposite to the direction of rotation R1 of the rotor, by the catch surface as the gripper passes close to the clamping wheel 10.1. Fig. 4B shows the roller 13.23 of gripper 13.13 approaching a clamping surface of the rotor, for clamping a portion of shrimp, in particular between the roller 13.23 and a detachable plate 13.30. The plate 13.30 is detachably attached to the rotor by means of screws 13.34, and comprises a portion 13.31 which forms a clamping surface with an abrasive surface finish. If desired, the plate can 13.30 easily be replaced with another plate, e.g. having a portion with different kind of surface finish.

Fig. 5A and 5B respectively show schematically an isometric view and a top view of the meat removing station 16 shown in Fig. 1. The meat removing station is here shown with a only single gripper 16.20 for reasons of clarity, though in practice the rotor 16.1 of the station 16 will have three such grippers along the circumference as shown in Fig. 1A. The gripper 16.20 is rotatably arranged on a shaft 16.23 which extends parallel to the axis of rotation A1 ' of the rotor 16.1 and is spaced apart therefrom. The gripper shaft 16.23 is provided with a gear wheel 16.24 which engages a main gear wheel 16.2 that is fixed to a central shaft 16.3 which coincides with the axis of rotation A1 ' of the rotor. The main gear wheel 16.2 of the meat removing station is stationary relative to frame 50, so that when the rotor 16.1 is rotated around its axis A1 ' in direction of rotation R1 ', the stationary main gear wheel 16.2 and the rotating gear wheel 16.24 at the end of the gripper shaft 16.23 together cause the moveable surfaces 16.21 , 16.22 of the gripper 16.20 to rotate in a same direction of rotation R2' as direction of rotation R1 of the rotor 16.1.

Rollers 16.30 and 16.31 are arranged on respective axles 16.32, 16.33 which extend through the central shaft 16.3 and perpendicular thereto. When the outer sides of gripper surfaces 16.21 and 16.22 contact the rollers 16.30, 16.31 , the moon-shaped moveable surfaces 16.21 , 16.22 are moved towards each other along direction P6 to engage the lateral sides of a shrimp.

Wheels 16.41 and 16.42 are fixed to central shaft 16 and moveably support the moveable surfaces 16.21 , 16.22 so that these can tilt and slide relative to the second axis of rotation A2, without rotating around the second axis of rotation. The wheels 16.41 , 16.42 are accommodated within the moveable surfaces such that each of the moveable surfaces can translate relative to its wheel along the second axis of rotation A2'. Pins 16.43 and 16.44 project from the wheels in a direction normal to the second axis of rotation A2' and extend into corresponding openings 16.44, 16.45. The pins thus allow the moveable surfaces 16.21 , 16.22 to rotate around a longitudinal axis of their respective pin, while blocking rotation of the moveable surfaces relative to their wheels 16.41 , 16.42 around the second axis of rotation A2'. Though in Fig. 5A the openings 16.44 and 16.45 are shown in cross-section for reasons of clarity, it will be clear that the pins are completely surrounded by the respective circumferential inner edges of these openings Fig. 5B further shows a spring 16.25 arranged for biasing the gripper surfaces to a position further away from each along the axis of rotation A2' of the gripper. The gripper surfaces thus both can be moved towards and away from a plane M which extends normal to the axis of rotation A1 '. Typically, if the meat of a shrimp is held between the two grippers, it will intersect the plane M.

As the central shaft 16.3 is stationary relative to the frame, the position at which, and extent to which, the moveable surfaces are moved towards each other and away from each other, is determined by the position of the rollers 16.30, 16.31 on the central shaft 16.3. The rollers 16.30, 16.31 and/or axles 16.32, 16.33 are therefore preferably attached to the central shaft 16.3 in an adjustable manner such that the position of one or both of the rollers along the axis of rotation A1 ' can be adjusted. Though not shown in this embodiment, the axles 16.32, 16.33 may for embodied as eccentric axles, so that by rotating the axles the positions of the rollers 16.30, 16.31 along the axis of rotation A1 ' can be set.

Fig. 5C shows a cross-sectional view of gripper 16.20, in which the spring 16.25 in the space between the inner gripper surfaces 16.41 and 16.42 and which is connected to said surfaces can be seen more clearly. The gripper is further provided with additional springs 16.26 and 16.27, each of which is attached at one end to a corresponding gripper surface at a side facing away from spring 16.25. The springs 16.26 and 16.27 are attached at their other sides to stops 16.28, 16.29 fixed to the gripper shaft 16.23,and are adapted for urging the inner gripper surfaces towards each other. The inner gripper surfaces 16.41 and 16.42 which are respectively connected to the springs, 16.25, 16.26 and 16.25, 16.27 can thus move axially relative to each other along the shaft 16.23, and can also rotate to some extent, e.g. rotate about an angle of at most 30° relative in directions P8 and P9 relative to the shaft 16.23. The gripper is thus adapted to adjust the orientation of the gripper surfaces 16.41 , 16.42 in dependence on the portion of shrimp that is gripped therebetween, thus substantially preventing the gripped portion from being crushed and further providing a better grip thereon. Figures 6A-6C schematically illustrate how the meat is removed from a shrimp at the meat removing station 16 during continuous rotation of both the clamping wheel 10.1 and of rotor 16.1 of the meat removing station in a direction of rotation R1 ' counter to the direction of rotation R5 of the clamping wheel. The rotor 16.1 is provided with a gripper, shown in Figs. 4A - 4C, for gripping the shrimp meat at the lateral sides thereof. When rotor 16.1 rotates the gripper to a position proximate to the clamp holding the shrimp, the gripper engages said lateral sides. At the same time a roller 17.1 of head stopper station 17 is moved towards the clamping wheel along direction P7 to a position in which it pushes against the head of the shrimp while the shrimp meat is being gripped, as shown in Fig. 6A. The pressure applied by the roller 17.1 prevents the carapace of the shrimp from being partially pulled out of the clamp by the gripper and also helps to squeeze the meat of the shrimp out of the carapace in a direction counter to direction of rotation R5. The head stopper station may be embodied as part of the meat removing station.

Further rotation of the rotor 16.1 and of the clamping wheel 10.1 subsequently cause the shrimp meat to be pulled away from the clamping wheel, while carapace of the shrimp remains clamped on the clamping wheel 10.1 , as shown in Fig. 6B. Finally, as the rotor 16.1 continues its rotation, the gripper opens, as shown in Fig. 6B, up to let the meat fall out of the gripper, e.g. along direction P5 into a container 20 for shrimp meat as shown in Fig. 1. A scraper 18 is arranged in the plane M (see Fig. 4B), for scraping off any portion of the shrimp that may still adhere to one or both of the gripper surfaces 16.41 and 16.42, thus ensuring that the portion is be released from the gripper surfaces and falls into the container 20.

After releasing the meat, that portion of the rotor 16.1 where the gripper is located is brushed by brush 14C.

Though Figs. 6A - 6C show a rotor with only a single gripper, it will be clear that preferably multiple grippers are provided on the rotor, so that one gripper may be used for gripping a shrimp, while another gripper is cleaned while it is not in contact with shrimp meat, e.g. by brushing or using a water jet. In particular, the rotor shown in Figs. 5A - 5C may comprise three such grippers, spaced equidistantly around the circumference of the rotor, as shown in fig. 1. Fig. 7 shows an isometric view of the head stopper 17 as part of the meat removing station

16. The head stopper comprises a stationary base 17.2, e.g. which is stationary relative to the frame 50 of Fig. 1. Moveable relative to the base is an arm 17.3 at the end of which a roller 17.1 is provided for contacting a head portion of a shrimp clamped on the clamping wheel 10.1. Rotating movement of cam 17.4 drives a reciprocating motion of the arm 17.3, and the roller at the end thereof, towards and away from the clamping wheel 10.1. This reciprocating motion is coupled with the rotation of the clamping wheel 10.1 in such a manner that the roller 17.1 of the head stopper is moved towards the clamping wheel when the shrimp from which the meat is to be removed close is enough to the meat removing station 16 for the grippers of the meat removing station to grip the meat.

As the roller 17.1 contacts the head portion of the shrimp and presses it against the clamping wheel 10.1 , the head portion of the shrimp can cause the roller 17.1 to rotate in a direction counter to the direction of rotation R5 of the clamping wheel, and the shrimp is smoothly pressed by the roller against the clamping wheel 10.1. At the same time the clamp on said wheel 10.1 which clamps the shrimp is loosened slightly, so that the head of the shrimp is mainly held against the clamping wheel 10.1 by the roller 17.1 of head stopper 17 instead of by the clamp of the clamping wheel. The reduced force with which the meat is clamped by the clamp facilitates removal of the shrimp meat from the shell by the meat removing station 16. Once the meat has been removed, the arm 17.3 is moved back to its retracted position.

In summary, the invention relates to a station for peeling a shrimp or part thereof while said shrimp is individually clamped on a clamping wheel that is rotatable along said station around an axis of rotation, comprising: a base and rotor connected thereto rotatable relative to said base around a first axis of rotation for a complete revolution; and one or more grippers, each rotatable relative to said rotor around its associated second axis of rotation and arranged for gripping a portion of said shrimp when said gripper is moved to a position close to where said shrimp is clamped on said clamping wheel during rotating movement of said rotor around the first axis of rotation while said gripper rotates relative to said rotor around its second axis of rotation, to separate said portion from a part of said shrimp which remains clamped on the clamping wheel. The present invention has been described above with reference to a number of exemplary embodiments as shown in the drawings. Modifications and alternative implementations of some parts or elements are possible, and are included in the scope of protection as defined in the appended claims.